Step-up ring



FIG. 1 is a front perspective view of a step-up ring in accordance with the present invention;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4. is a top view thereof,

FIG. 5 is a bottom view thereof;

FIG. 6 is a left side view thereof; and,

FIG. 7 is a right side view thereof.

The broken lines shown in the drawing depict portions of the step-up ring that form no part of the claimed design. 

CLAIM The ornamental design for a step-up ring, as shown and described. 